A graphene-based material such as graphene and graphene oxide, which is a derivative of graphene, has been expected as a material capable of realizing a new function or a new performance which cannot be obtained in a semiconductor material, which is represented by silicon, in the related art. Graphene represents a material that corresponds to one layer of graphite that has a layer-shaped structure of carbon atoms, and a derivative in which oxygen atoms are coupled to the graphene is referred to as graphene oxide. Such a graphene-based material is a very thin two-dimensional material, and thus it is possible to construct a switching device of an ultrathin conduction channel, and the like which cannot be obtained in a silicon semiconductor transistor of the related art. In addition, such a graphene-based material exhibits unique characteristics such as very high electron mobility and a very high quantum Hall effect, and thus the graphene-based material has attracted attention as a material of various electronic devices such as a high-frequency transistor and a quantum device.
It is necessary to control electrical characteristics of a material so as to realize an electronic device such as a switching device by using the graphene-based material. To achieve this, it is preferable to control a bandgap in an electron state of the graphene-based material. However, graphene has metal characteristics, and thus there is a problem in that graphene has no bandgap. As means for solving the problem, a method of applying an electric field that is vertical to a layer surface direction of a two-layer graphene film, a method of thinning single-phase graphene, a method of adsorbing hydrogen atoms to a graphene surface, a method of using graphene oxide, and the like (refer to NPL 1, NPL 2, NPL 3, and NPL 4) have been suggested.
In the method of applying the vertical electric field, when application of a voltage is stopped, formation of the bandgap is also stopped. According to this, a device function such as switching is volatile. The thinning method, the method of adsorbing hydrogen atoms, and the method of using the graphene oxide can constantly form a bandgap. However, in a case of being applied as a material of an electronic device such as a field effect transistor, the function such as switching is a volatile function that disappears when stopping application of an external voltage for control. The volatility becomes a problem in application to an electronic device such as a nonvolatile memory which is required to continuously exhibit functionality even when stopping application of a voltage.